Crude oils, as extracted from their original source, are not suitable for human consumption due the presence of high levels of contaminants—such as free fatty acids, phosphatides, soaps and pigments—which may be toxic or may cause an undesirable colour, odour or taste. Crude oils are therefore refined before use. The refining process typically consists of three major steps: degumming, bleaching and deodorizing. An oil obtained after completion of the refining process (called a “refined oil”) is normally considered suitable for human consumption and may therefore be used in the production of any number of foods and beverages.
It has now been found that the crude oil refining process itself contributes to the introduction, of various levels of 3-monochloropropane-1,2-diol fatty acid esters (3-MCPD esters) and glycidyl esters. 3-MCPD ester and glycidyl ester amounts are depending on oil type and refining process. Most vegetable oils show 3-MCPD ester contents between 200-800 ppb and Glycidyl ester content below 500 ppb, but for palm oil or specific process conditions values even above 5000 ppb might be found.
Free 3-monochloropropane-1,2-diol (3-MCPD) has been identified as a contaminant for a long time in various foods. Recent studies have identified 3-MCPD fatty acid esters in refined edible fats and in fat-containing foods. 3-MCPD esters are formed at high temperatures, in particular during deodorization. Also 2,3-epoxy-1-propanol (glycidol) is formed in the deodorization step. Both glycidyl esters and 3-MCPD esters are associated with a possible carcinogenic effect.
EP 2 449 070 describes a process for removing unwanted propanol components from unused triglyceride oil including contacting the contaminated oil with an adsorbent.
A further suggestion for reducing 3-MCPD ester content is made in WO2010/036450 (Süd-Chemie). It is based on a modified refilling process which uses very intensive bleaching (with high amounts of bleaching clays).
WO2012/107230 describes an alternative process for the reduction of 3-MCPD and/or glycidyl ester content and wherein the process comprises subjecting an oil to the following steps, in order: a) a bleaching step, b) a deodorization step, c) a final bleaching step, and d) a final deodorization step wherein the final deodorization step d) is carried out at a temperature at least 40° C. lower than deodorization step b).
It would be desirable to have a simple, mild but effective process for the removal of these unwanted propanol fatty acid esters.
The current invention provides such a process.